I dont really mind option to pick reward ...
And the UI for doing that dont bother me ...
But i still dislike this feature for two reasons:
1) NPCs allways mention "a reward" ...
I dont think it would be too hard to say instead something like "i have theese, pick one" to acnowledge what is actualy happening. :-/
2) Those rewards materialize out of thin air ...
This really bothers me a lot.
I know it requires metagaming, but thats not the point here ... NPC is "offering" me something, so if i kill that NPC i expect it to be there. :-/
This sucks.

Same problem i have with things dissapearing from Vendor inventory, when you kill them.